This invention relates to a method and apparatus for deregistering crimped multifilament polyamide tow and the product produced by this method and, more particularly, it relates to maintaining the tension on the crimped tow substantially constant during the stretching operation used to deregister the crimped tow.
It is known to crimp synthetic filaments; however, when high degrees of crimp are imparted to the tow for particular end uses and the tow is then cut to staple, this high crimp level actually inhibits further processing because the staple produced exhibits excessive cohesion and, as a consequence, the cut staple segments are difficult to process in worsted and woolen systems to make yarns. More particularly, when such fibers are carded to comb them to parallelism they may, because of the excessive cohesion, be entangled to such a degree that portions of the fibers are stretched until crimp is removed permanently or the filaments break. It is known that by deregistering the tow by stretching, i.e. redrawing at a fixed draw ratio, cohesion is reduced and mill processing of staple cut from the tow improves. However, when deregistering takes place using crimped tow made in a so-called split process where the ends of crimped tow are joined to accommodate a continuous cutting and baling operation, the joined regions cannot be elongated during stretching to deregister the tow and, consequently, filaments break or perhaps the tow itself will break causing a disruption in the process. In addition, local variations in crimp level associated with stops and starts of a draw line, small changes in moisture content or temperature, or storage conditions for split process product are continuously occurring and, therefore, adjustments in tension are continuously needed to maintain final product uniformity.